Presently, uranium is being recovered from phosphoric acid by solvent extraction. In the first cycle of preferred processes using a di-2-ethylhexylphosphoric acid/trialkylphosphine oxide (D2EHPA/TOPO) solvent mixture, the uranium is stripped from the solvent using phosphoric acid containing a high concentration of ferrous iron. The uranium can be recovered from this strip acid by first oxidizing the acid and then re-extracting the uranium, preferably with a D2-EHPA/TOPO solvent mixture in a second cycle extraction. The uranium can be recovered from the second cycle solvent using an ammonium carbonate strip solution. This process is well known in the art, and is taught for example by Hurst et al., in U.S. Pat. No. 3,711,591; Elikan et al., in U.S. Pat. No. 3,966,873 and Sundar, in U.S. Pat. No. 4,002,716.
In this second cycle operation, uranium stripped organic is recycled back to re-extract more uranium from the oxidized first cycle product acid. However, an iron-ammonium-phosphate precipitate is formed. The precipitate has been identified as primarily Fe.sub.3 NH.sub.4 H.sub.8 (PO.sub.4).sub.6. Wiewiorowski et al., in U.S. Pat. No. 4,105,741, dealing primarily with iron removal from phosphoric acid, also recognized this problem. Wiewiorowski et al. attempted to eliminate this precipitate, which interferes with uranium recovery, by washing the second cycle solvent with an outside stream of a purified acid selected from sulfuric, hydrochloric, nitric or iron-free phosphoric acid. However, this requires a large supply of expensive, pure acid, and requires a disposal of the partially neutralized acid. What is needed is an inexpensive means to eliminate the precipitate.